The present invention relates to wireless network services, and more particularly to the Short Message Service (SMS) feature and its implementation in a Wireless Number Portability (WNP) environment.
Several FCC Orders on Telephone Number Portability, CC Docket No. 95-116 (i.e., First Report and Order, released Jul. 2, 1996; First Memorandum Opinion and Order on Reconsideration, released Mar. 11, 1997; and Second Report and Order, released Aug. 18, 1997) mandate that all Commercial Mobile Radio Service (CMRS) providers participate in Number Portability (NP), i.e., provide the capability to deliver calls from their networks to ported numbers. NP in wireless networks is referred to as Wireless Number Portability (WNP). Because wireless subscribers are mobile and are not associated with any fixed location or serving switch, there are many special considerations when implementing number portability in the wireless environment.
The purpose of WNP is to allow a wireless subscriber to change its subscription to a different wireless service provider while the number that callers dial to reach the subscriber remains unchanged. Prior to number portability in the wireless arena, service providers used a single number--the Mobile Identification Number (MIN)--not only for delivery of calls to the wireless subscriber, but also for registration and authentication when the wireless subscriber moves from one service area to another. For a 10-digit MIN of the form NPA-NXX-XXXX (traditional North American Numbering Plan format), the first six digits were sufficient to route a call and to register a subscriber, i.e., to determine the service provider and home network of the subscriber. If the single MIN became portable, six digits would no longer be sufficient, and registration would require a 10-digit translation or database dip.
To solve this problem, the wireless industry has decided to assign two independent numbers to a subscriber--a Mobile Directory Number (MDN) and a Mobile Station Identification Number (MSID). The MDN is a dialable number in the NPA-NXX-XXXX format. The MSID can be in the format of either a Mobile Identification Number (MIN) or an International Mobile Station Identification (IMSI). The MDN will be portable so that when a subscriber changes service providers, the MDN can be retained by the subscriber. The MSID belongs to a specific service provider's network, so that when the subscriber changes service providers, it receives a new MSID. Before a particular subscriber is ported, the MDN and MSID will most likely be identical, if the MSID is in MIN format. When a subscriber ports to a new service provider, it surrenders its old MSID to the donor network and receives a new MSID from the network of the new service provider. The ported subscriber's MDN remains unchanged. Mobile registration continues to use the first six digits of the MSID to determine the subscriber's home network.
For call routing in a WNP environment, the wireless industry has agreed to use the wireline call routing technique, known as Location Routing Number (LRN) Routing. The LRN is a 10-digit number in NPA-NXX-XXXX format that identifies the subscriber's serving switch. A Number Portability database (NP-DB) maintains a mapping of ported MDN numbers to their serving switch LRNs. The NP-DB may be, for example, a Service Control Point (SCP). During call routing and processing, the network queries the NP-DB for the serving switch LRN corresponding to the subscriber's MDN.
The Short Message Service (SMS) feature provided by wireless networks provides short text messaging from or to a wireless device. Before the implementation of WNP, a calling party using the SMS feature initiates a short message and provides the called party's MIN to the originating network. The originating network then routes the short message to the destination home system using the dialed MIN. In a pre-WNP environment, the first six digits of the dialed MIN provide sufficient routing information for the short message to be delivered to the destination home system of the short message receiver.
FIG. 1 illustrates the network components that may be involved in routing and delivering a short message in a pre-WNP environment. The procedures to process and deliver an SMS message are defined in Interim Standard 41 (IS-41) Revision C, a signaling protocol used in wireless networks. Referring to FIG. 1, within network 10, a short message originates at a subscriber in originating system 12 and is destined for a mobile station (MS) currently served by destination serving system 14. Destination home system 16 is the home system of the destination MS. Communications regarding routing and delivery of the short message, as well as delivery of the short message itself, occur over signaling network 18. The originating subscriber, not particularly shown for the sake of clarity, is served by Mobile Switching Center (MSC) 20 in originating system 12. Originating home system 13 contains Message Center (MC) 22 for storing short messages. The destination MS, not particularly shown for the sake of clarity, is served by MSC 24 in destination serving system 14. Destination home system 16 contains MC 26, which is coupled to Home Location Register (HLR) 28, a database that stores subscriber information for wireless networks. Alternatively, if MC 26 and HLR 28 are not co-located, they may communicate via signaling network 18.
FIGS. 2 and 3 illustrate two existing methods of routing an SMS message in a pre-WNP environment, known in the art as direct routing and force indirect routing, respectively. In direct routing, the short message is sent to the destination home MC directly from the sender's serving MSC. In force indirect routing, the short message is routed from the sender's serving MSC through the sender's home MC to the destination home MC.
FIG. 2 illustrates the existing procedures for delivering an SMS message using direct routing. With reference to FIGS. 1 and 2, originating system MSC 20 routes an SMS Delivery Point to Point (SMDPP) message over signaling network 18 directly to destination home MC 26 by performing an MIN.sub.receiver -to-MC mapping, i.e., mapping the MIN of the destination provided by the originating subscriber to the address of the destination home system MC associated with that MIN. This mapping requires only the first six digits of the MIN, which uniquely define the destination home system. The mapping is done via Global Title Translation (GTT) at a Signaling Transfer Point (STP) in signaling network 18 (not shown), via an internal table at originating system MSC 20 (not shown), or via a third party performing similar functions (not shown). Destination home MC 26 responds with an smdpp positive acknowledgment over signaling network 18. When destination home MC 26 receives the SMDPP request, it contacts HLR 28 to obtain an SMS routing address for destination MSC 24. "SMSREQ[MIN]" in FIG. 2 corresponds to the MC 26 request from HLR 28. If HLR 28 has a current SMS routing address for MSC 24, HLR 28 returns the address to destination home MC 26. This is noted in FIG. 2 as the "smsreq[SMSADDR]" between HLR 28 and MC 26. Otherwise, HLR 28 requests an SMS routing address from destination MSC 24, which request is designated in FIG. 2 by "SMSREQ[MIN, ESN], and returns that address, SMSADDR, to destination home MC 26. This is noted in FIG. 2 by the "smsreq[SMSADDR]" flowing from MSC 24 to HLR 26 to MC 26. Destination home MC 26 then forwards the SMDPP toward destination MSC 24 using the SMS routing address, SMSADDR.
FIG. 3 illustrates the existing procedures for delivering an SMS message using force indirect routing. With reference to FIGS. 1 and 3, originating system MSC 20 routes an SMDPP indirectly to originating home MC 22 by performing an MIN.sub.sender -to-MC mapping, i.e., mapping the MIN of the originating subscriber to the MC of the originating home system. This mapping is done either via GTT at an STP in signaling network 18 or via an internal table at originating system MSC 20, not particularly shown. Originating system MC 22 responds with an smdpp positive acknowledgment. Originating system MC 22 then forwards the SMDPP to destination home MC 26 by performing an MIN.sub.receiver -to-MC mapping, i.e., mapping the MIN of the destination provided by the originating subscriber to the MC of the destination home system associated with that MIN. This mapping requires only the first six digits of the MIN, which uniquely define the destination home system. The mapping is done either via GTT at an STP in signaling network 18 or via an internal table at originating system MC 22, not particularly shown. Destination home MC 26 responds with an smdpp positive acknowledgment. When destination home MC 26 receives the SMDPP request, it contacts HLR 28 to obtain an SMS routing address for MSC 24. "SMSREQ[MIN]" in FIG. 3 corresponds to the MC 26 request from HLR 28. If HLR 28 has a current SMS routing address for MSC 24, HLR 28 returns the address to destination home MC 26. This is noted in FIG. 3 as the "smsreq[SMSADDR]" between HLR 28 and MC 26. Otherwise, HLR 28 requests an SMS routing address from destination MSC 24, which request is designated in FIG. 3 by "SMSREQ[MIN, ESN], and returns that address, SMSADDR, to destination home MC 26. This is noted in FIG. 3 by the "smsreq[SMSADDR]" flowing from MSC 24 to HLR 26 to MC 26. Destination home MC 26 then forwards the SMDPP toward destination MSC 24 using the SMS routing address, SMSADDR.
When wireless networks implement WNP, the MDN and MSID will be separate numbers. As a result, SMS will fail when delivering a short message to a ported MS. When the destination MS ports to another service provider, it receives a new MIN, as the mobile station identification (MSID) number, and retains the existing MDN. The first six digits of the new MSID identify the new service provider to the network. However, when originating a short message to the ported MS, the sender will provide only the destination MDN to the network since MINs are transparent to subscribers. The MDN alone does not provide the originating system enough information to derive the identity of the destination home system. To determine the destination home system, the originating system would have to perform a full 10-digit translation to obtain a physical address corresponding to the destination home system. Such a translation process requires extremely large translation tables, and synchronization of data in these translation tables would make it difficult and impractical to perform 10-digit translations.
It is desirable, therefore, to provide a scheme for locating a ported subscriber's destination home MC in a WNP environment without performing a 10-digit translation in the originating system. It is also desirable to provide a scheme for routing SMS messages using the MDN of the destination MS. It is even more desirable to provide such a scheme that has minimal impact on existing network elements and requires a minimum of new capabilities.